THE MANNER OF COPULATION IN A TURBEL- 

 LARIAN WORM, PLAN ARIA MACULATA. 1 



ROBERT A. BUDINGTON. 



During the summer of 1920, while observing rather large num- 

 bers of flatworms, Planaria maculata, the writer chanced upon a 

 quite ideal opportunity for watching copulation habits in that 

 species. The worms were in a watch-glass which was easily 

 transferred to the stage of a binocular dissecting microscope, 

 and the attitude and relation of the mating worms thus became 

 readily noted. Later they were killed, while still copulating, 

 with a hot corrosive-acetic mixture; and although the worms 

 separated during this treatment, the fixation was rapid enough so 

 that the penes of the killed worms were preserved in very pro- 

 truded condition. 



Referring to the incident in conversation with several zoologists, 

 it seemed that they had never observed turbellarian copulation, 

 nor did they remember having seen it described. On looking for 

 data regarding it, it has not been possible to find any account of it 

 either in the larger treatises or in more extended special papers on 

 flatworm anatomy and behavior. Curtis, '02, who worked upon 

 the "Life History, Normal Fission, and Reproductive Organs" 

 of this same species for three years, informs me that he did not 

 observe copulation. His studies were so extended, both in 

 numbers used and in period of time, that one is inclined to 

 conclude that either the procedure is not very frequent or that it 

 is of short duration in any given instance. 



Since there seems this gap in the recorded descriptions of this 

 worm's total behavior, the following paragraphs are offered as 

 supplementing our knowledge of it, as well as indicating what may 

 be the impregnation process in turbellarians in general; for if, 

 indeed, the process has not been much or at all studied, there may 

 exist even so elementary a question as to whether or not the 

 short copulatory organ is protruded through the atrial pore at all ; 



1 From the Department of Zoology, Oberlin College, and the Marine Biological 

 Laboratory, Woods Hole. 



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